K.P. Kwong

Dietary exposure to aluminium of the Hong Kong population.

A total of 256 individual food samples were collected in Hong Kong for aluminium testing. Most of food samples were analysed in ready-to-eat form. High aluminium levels were found in steamed bread/bun/cake (mean: 100–320 mg kg−1), some bakery products such as muffin, pancake/waffle, coconut tart and cake (mean: 250, 160, 120 and 91 mg kg−1, respectively), and jellyfish (ready-to-eat form) (mean: 1200 mg kg−1). The results demonstrated that aluminium-containing food additives have been widely used in these food products. The average dietary exposure to aluminium for a 60 kg adult was estimated to be 0.60 mg kg−1 bw week−1, which amounted to 60% of the new PTWI established by JECFA. The main dietary source was “steamed bread/bun/cake”, which contributed to 60% of the total exposure, followed by “bakery products” and “jellyfish”, which contributed to 23 and 10% of the total exposure, respectively. However, the estimation did not include the intake of aluminium from natural food sources, food contact materials or other sources (e.g. drinking water). Although the results indicated that aluminium it is unlikely to cause adverse health effect for the general population, the risk to some populations who regularly consume foods with aluminium-containing food additives cannot be ruled out.

Dietary exposure to antimony, lead and mercury of secondary school students in Hong Kong

The aim of this first study was to determine the dietary exposure of antimony, lead, mercury in foodstuffs consumed by secondary school students in Hong Kong. Around 100 composite food items were purchased and then cooked prior to analysis. Antimony was measured by hydrogen generation (HG)/inductively coupled plasma–mass spectrometry (ICP–MS), while lead was determined by ICP–MS. Total mercury was measured by cold vapour atomic absorption spectrometry. The detection limits for antimony, lead and total mercury were 1, 0.6 and 3 µg kg−1, respectively. The dietary intake of antimony, lead and total mercury for an average secondary student were estimated to be 0.252, 1.98 and 0.92 µg (kg bw)−1 week−1, respectively. The dietary intake of antimony, lead and total mercury for high-consumer secondary student were estimated to be 0.567, 5.09 and 2.33 µg (kg bw)−1 week−1, respectively. The main contribution to antimony, lead and mercury were milk, vegetables and seafood, respectively. The Tolerable Daily Intake (TDI) of antimony, as recommended by WHO, is 6 µg (kg bw)−1 week−1, while the Provisional Tolerable Weekly Intakes (PTWI) of lead and mercury, as recommended by JECFA, are 25 and 5 µg (kg bw)−1 week−1, respectively. The estimated exposure values for secondary school students were compared to these safety reference values. For the relevant population, this study confirms the low probability of health risks from these metals via food consumption.

Mercury and methylmercury levels in the main traded fish species in Hong Kong

Levels of total mercury (tHg) and mono-methylmercury (MeHg) were measured in 280 different fish, including fresh/frozen raw whole fish of 89 different species and canned tuna fish of three different species, that are traded mainly in Hong Kong, China. These samples were purchased from different commercial outlets between April and August 2007. All samples of raw whole fish were identified at species level by the Agriculture, Fisheries and Conservation Department. The range for tHg and MeHg of all samples were 3–1370 and 3–1010 µg kg−1, respectively, with medians of 63 and 48 µg kg−1, respectively. The results show that, according to Hong Kong legislation, the products on the market are generally ‘safe’. A total of 277 samples (99?) contained tHg and MeHg below the legal limit of 500 µg kg−1. The remaining three samples of alfonsino (species: Beryx splendens) were found to contain tHg and MeHg at levels higher than 500 µg kg−1 (tHg: 609–1370 µg kg−1; MeHg: 509–1010 µg kg−1). The ratios of MeHg to tHg in the different fish species ranged from 0.46 to 0.99.

Dietary exposure of Hong Kong secondary school students to total mercury and methylmercury from fish intake.

Fish is the main source of dietary exposure to methylmercury (MeHg), which is a public health concern owing to its potential neurotoxicity. To evaluate the public health risk, this study estimated the total mercury (tHg) and MeHg exposure from fish intake in Hong Kong secondary school students. Median tHg and MeHg concentrations of 280 samples purchased from different commercial outlets (covering 89 species of whole fish and three types of canned tuna), together with the local food consumption data of secondary school students obtained by semi-quantitative food frequency questionnaire in 2000, were used to estimate dietary exposure from fish intake for the average and high consumer (95th percentile exposure). For tHg, the median concentration was 63 µg kg–1 (range 3–1370 µg kg–1) and estimated exposures ranged 0.5–0.6 µg kg–1 body weight (bw) week–1 for an average consumer and 1.6–1.9 µg kg–1 bw week–1 for a high consumer. For MeHg, median concentration was 48 µg kg–1 (range 3–1010 µg kg–1) and estimated dietary exposures were 0.4–0.5 µg kg–1 bw week–1 for an average consumer and 1.2–1.4 µg kg–1 bw week–1 for a high consumer. These values are below the respective provisional tolerable weekly intake (PTWI) established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA). The health risk is greater for high consumers since MeHg exposures may approach or exceed the PTWI when other dietary sources are taken into account.

Dietary exposure to DDT of secondary school students in Hong Kong.

The aim of this study was to determine the dietary exposure of DDT in foodstuffs consumed in Hong Kong by secondary school students in Hong Kong in 2005. Food samples of domestic or imported food were collected randomly from local markets for the determination of DDT. The analytical method for this survey was based on isotope dilution technique. DDT isomers were determined at parts per billion (microg kg(-1)) levels in foods by pressured fluid extraction followed by gel permeation column cleanup and gas chromatography with mass spectrometry detection. Among the 98 composite samples, 25 were found positive with DDT levels greater than the limit of quantitation (LOQ) (1 microg kg(-1) for each isomer of DDT). Only two of the meat products were found to contain low levels of the metabolites of DDT. A number of fish and shellfish were found to contain not just the metabolites of DDT, but also parent DDT. The main contribution to DDT was from seafood. The dietary intake of DDT for an average and high secondary school student consumers were estimated to be 0.145 and 0.291 microg kg(-1) bwd(-1), respectively. Both levels fell well below the Provisional Tolerable Daily Intake (PTDI) of 10 microg kg(-1) bwd(-1) established by the Joint Food Agriculture Organization/World Health Organization Meeting on Pesticide Residues (JMPR). It was concluded that both the average and high secondary school student consumers were unlikely to experience major toxicological effects of DDT.

Ethyl carbamate in fermented foods and beverages: dietary exposure of the Hong Kong population in 2007–2008

To evaluate the potential public health risk of ethyl carbamate (EC), EC exposure from fermented foods and beverages for Hong Kong population was estimated. In 276 samples analysed, EC was detected (limit of detection (LOD) at 0.4 µg kg−1) in 202 samples (73%), with higher levels in fermented red bean curd (150–650 µg kg−1) and yellow wine (140–390 µg kg−1), while low or non-detected (ND) in preserved vegetables (ND–10 µg kg−1) and fermented tea (ND–15 µg kg−1). The estimated dietary exposure from all fermented foods and beverages was 8.27 ng kg−1 bw day−1, while exposure excluding alcoholic beverages was 5.42 ng kg−1 bw day−1, with calculated margins of exposure (MOEs) at 3.6 × 104 and 5.5 × 104 respectively. The risk of adverse health effects was low for the average population but higher (MOE of 103) for high consumers of alcoholic beverages especially habitual drinkers of alcoholic types with high EC contents.

Dietary exposure to chloropropanols of secondary school students in Hong Kong

This paper reports levels of 3-monochloropropan-1,2-diol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) in a wide range of food items and estimates their dietary exposure for secondary school students in Hong Kong. Dietary exposure to chloropropanols was estimated using local food consumption data obtained from secondary school students in 2000 and the concentrations of 3-MCPD and 1,3-DCP in food samples taken from the local market. The dietary exposure to 3-MCPD for an average secondary school student consumer was estimated to be 0.063–0.150 µg kg−1 body weight (bw) day−1, whilst that for the high consumer was 0.152–0.300 µg kg−1 bw day−1. Both estimates fell below the provisional maximum tolerable daily intake of 2 µg kg−1 bw established by the Joint Expert Committee on Food Additives (JECFA) and amounted to less than 20% of this safety reference value. The dietary exposure to 1,3-DCP for an average secondary school student consumer was estimated to be 0.003–0.019 µg kg−1 bw day−1, whilst that for the high consumer was 0.009–0.040 µg kg−1 bw day−1. The resulting margins of exposures were of low concern for human health. It could be concluded that both the average and high secondary school student consumers were unlikely to experience major toxicological effects of 3-MCPD and 1,3-DCP.